The present invention relates to display controllers for digital display devices such as liquid crystal displays, plasma displays and progressive-scan televisions.
New digital displays such as liquid crystal display (LCD) panels are experiencing rapid adoption by consumers. In addition to being flat light-weight and thin, the digital display offers high resolution rendering of text, graphics and video information. The display is controlled by continuously feeding dot data to the display. The data is organized into individual pixels, rows of pixels, and full-page frames. A set of rows makes up a frame, which is one full page of the display. LCD data is continuously sent to the LCD panel to refresh the display frame.
Since the digital display can crisply render high resolution images, any disturbance or video artifact becomes easily visible on the display. For example, video noise typically appears as undulating twinkling bits on the display. Further, when low resolution video/graphic data is provided to the display, the input video is scaled to fit the higher display resolution, resulting in a lack of sharpness. Additionally, even if high resolution video/graphic data is provided to the display, certain display data may be devoid of fine details in the image (out-of-focus) or otherwise lack high contrast in local areas of the image. Such input with noise and/or lack of sharpness can be visually undesirable.
As mentioned in U.S. Pat. No. 4,972,256 entitled “Method of enhancing image sharpness for image reproduction using sharp/unsharp signal processing,” the technique of visually enhancing sharpness of an image by amplifying density difference between contours of respective patterns in the image for use in reproducing the image with a process color scanner or the like is well known in the art. In such a conventional technique, an unsharp signal is obtained by taking the weighted average of respective image signals in a plurality of pixels arranged in the form of a matrix. A sharpness enhancement signal is generated from the unsharp signal and an image signal (sharp signal) of a central pixel of the matrix. The sharpness enhancement signal is added to an original image signal. A signal obtained by such addition is stored as an image signal expressing an image in which sharpness is enhanced.
Also, a software application such as Adobe Photoshop® allows a user to select a sharpening filter which produces a pleasing amount of sharpening for a picture. Photoshop presents a user with a control panel which can be used to set parameter values defining a sharpening filter. Once the user has selected a set of filtering parameters, the application creates the desired filter and applies the filter to the picture.